OBJECTIVETo investigate the risk of hidden blood loss about applying rivaroxaban after total hip arthroplasty.

METHODSFrom October 2009 to May 2012,88 patients with femoral head necrosis were treated with primary total hip arthroplasty. All the patients were divided into Rivaroxaban group(44 cases)and control group(44 cases). There were 25 males and 19 females in the Rivaroxaban group, with an average age of (58.48 +/- 15.19) years old; in the control group,24 patients were male and 20 patients were female, with an average age of (61.11 +/- 13.54) years old. The patients in the Rivaroxaban group took Rivaroxaban orally from the first day after operation with a dose of 10 mg each day, and treatment course was 14 days. The patients in the control group took placebo orally at the same time. Dominant blood loss and transfusion were recorded, blood routine examinations were taken before operation and at 3 days after operation. The total blood loss and hidden blood loss were calculated according to the formula.

RESULTSThe mean total blood loss was (1509.56 +/- 325.23) ml and the hidden blood loss was(581.47 +/- 215.01) ml, accounting for (37.88 +/- 10.42)% in the Rivaroxaban group. The mean total blood loss was (1262.30 +/- 397.95) ml and the hidden blood loss was (395.59 +/- 97.33) ml, accounting for (30.62 +/- 0.20)% in the control group. The total blood loss, hidden blood loss and transfusion in the Rivaroxaban group was significantly more than those in control group,b ut there was no significant difference on dominant blood loss between two groups.

CONCLUSIONRivaroxaban increased the overall bleeding risk of total hip arthroplasty, especially hidden bleeding risk, which should be careful used.